Smell Sense And The Missing Pheromone
By Melissa Porter

We have five senses and smell just may be the most powerful of them. It is through life experience that we learn what should smell good and what smells bad. What we think about a waft from a barrel of hot, salty boiled peanuts or the blend of potatoes, lobster, and sausage will either make our mouth water or our nose shrivel up in disgust. Our sense of smell drives hunger, memory, emotions, and attraction.

When I was a teenager, my first boyfriend wore Drakkar Noir, a popular cologne in the early 1990s. Still to this today when I catch a hint of the unique scent, I’m reminded of a moment from our multi-year relationship. He was my first true crush, my first love, and my best-friend. Drakkar Noir will forever bring a little smile to my face as I recall my memories of that time.

Just behind your nose in your nasal passages are sensory cells about the size of a postage stamp. It’s these little receptors that pick up the molecules of odor as they waft by. Some may cause us to have an obvious physical or emotional response, while others are simply noticed only by our subconscious.

As young children, every scent is new and curious. It isn’t until we are about four years old that societal influence begins to shape our brain’s idea about what smells good or bad. Curiosity is the reason that children are intrigued by their waste. It isn’t until an adult tells them that it smells bad does a child develop the idea that poop stinks. Boiled peanuts and a Low Country Boil are a familiar scent to anyone who grew up in the South. However, those from other parts of the country may find the smell of salted water and hot peanuts or a mix of seafood, meat, and vegetables unappetizing. Every region of the country and the world has their unique specialty food that, at first smell, is unappealing to outsiders. Could you imagine eating fermented shark? Or what about a cheese that smells like your feet after a hot summer day trapped in your shoes? Fermented shark is a delicacy in Iceland. Camembert from Normandy, France looks like brie, but has a more pungent aroma often described as stinky feet, ammonia, or cabbage depending on the sense of smell you’ve developed.

The tongue has over 100,000 taste buds that sends our brains five distinct sensations, while the 1,000 sensory cells in the nose can identify ten different odors: citrus, chemical, fragrant, fruity, mint, pungent, sweet, toasted and nutty, woody and resinous, or decayed. Everything emits one or a combination of these smells as odor molecules. When they reach our nose, they bind to our sensory cells, or olfactory receptors, which tells our frontal lobe that a smell has been detected.  What happens from there is subjective based on your life experiences.

Scientists have been trying to crack the code to understanding the human sense of smell. It was not until 2014 that researchers at Rockefeller University discovered that our mind has the ability to blend the ten odors to make over one trillion individual distinct scents. It was previously believed that we could only identify 10,000 different smells, but that was based on a study from 1927.

A study published in 2012 showed that our olfactory system can detect fear and disgust. Researchers had men who used scent-free products and stopped consuming items that produced a scent when released through the skin. Men watched movies that triggered emotional responses, while scientists collected their sweat. The female participants completed a visual search test, while unknowingly exposed to the sweat of their study counterparts. The women displayed physical movements and facial expressions in accordance with the emotional sweat for disgust and fear.

Subconscious Smells

Every human has their own unique scent, much like a fingerprint. For centuries, scientists have tried to discover the odor molecule that intrigues adults, the pheromone. We want to know if we smell attractive? If not, can we smell attractive?

Adolf Butenandt, a German scientist, studied silkworm moths for twenty years. Adolf and his team searched for the hidden thing that even the Ancient Greeks knew existed, a sex scent. The Greeks believed female dogs sent secret signals to male dogs miles away, without a sound. They discovered that male dogs would chase a rag previously rubbed on a female dog in heat. It had to be through the power of smell. Adolf discovered a single molecule was responsible for creating a reaction in the male moth. Since Adolf’s study of the silkworm moths, a pheromone molecule has been discovered in both male and female animals across the animal kingdom. The molecule has been identified in goldfish, lobster, insects, and nearly every mammal. All the scientists who discovered the pheromone molecule in these animals used Adolf’s scientific method to find them. When he chose the silkworm moth, he accidently found the perfect subject to allow him to track his method. He needed half a million moths to obtain enough material for a chemical analysis. Adolf chronicled his systematic approach to analysis and synthesization of silkworm moth pheromones. So, what about the human pheromone? It may shock you to discover, no one knows. Despite the number of products available on the market, a human pheromone molecule has yet to be identified. There are theories that it might exist in the armpit. The armpit is common to both men and women. It is a location that changes when we all begin puberty. The body secretes more in this area than others, some stinky and some odorless. The armpit reacts to our emotional states, like receiving a flirtation from a love interest, and begins to sweat when we are nervous or excited. Yet, there is no evidence a human pheromone exists here, or anywhere else.

Elicit Response

Scientists have demonstrated natural human body odor elicits a response in other humans. Researchers have observed, since the 1970s, a change in a woman’s menstrual cycle when she’s exposed to another woman’s sweat. Another study found that a man’s testosterone level increases when he smells the scent of an ovulating woman. There has yet to be a study that has found the specific cause or potential molecule that stirs the reaction. These studies have lead researchers in circles and led them to hypothesize that perhaps human pheromones are more complex and may be a “modulator” pheromone that changes response based on the mood or mental state of the receiver.

Researchers in France changed their tact, deciding to start over. Upon accessing the most recent studies, they decided to take a look at newborns. We know that infants have a natural relationship with their mother, however, we do not understand why. Could it be that babies are attracted to their mother’s scent? If so, where does the smell originate?

When a mammal is born it needs to have its first milk within the first few hours otherwise it is at risk of death. Non-human mammals easily suckle and achieve their first milk without many issues. Humans, on the other hand, might need coaching to learn how to attach to their mother for milk. If you poke the cheek of a newborn, they instinctively attempt to suckle. The French researchers are using this instinct as a signal in their odor study. Placing a clean tube under the nose of a sleeping infant elicits no response. Filling that same tube with a few drops of milk from any woman causes the baby to start suckling. What invisible smell could the baby be reacting to?

Love Potion Number 9

While we await researchers to discover the molecule that could make finding a life mate easier, do not spend money on false pheromone potions. There is no Love Potion Number 9.

Humans are complicated beings. We are also complicating the discovery of the human pheromone. Scientists say the one thing that has made discovering the human odor molecule harder is our ability to affect our response. Just as we develop our sense of smell based on societal standards, we have also learned to adjust our emotional and physical responses.